The saturable mechanism of tyrosine (TYR) uptake by the membrane of red blood cells incubated at 37 °C has been studied in normal subjects and psychiatric patients. This uptake is markedly inhibited by incubation at 0 °C, and weakly inhibited by iodoacetic acid and ouabain. The uptake of TYR is significantly lower in unipolar- and bipolar-depressed patients, and significantly higher in schizophrenics compared to normal controls. These results indicate a possible disturbance of functional capacity of membrane transport in some psychiatric diseases.
Based upon 65 fawns marked in spring a few days after birth and captured again during the following winter in Trois-Fontaines reserve (eastern France), we demonstrate that body weight reached at the onset of the winter is independent of the early growth in roe deer (Capreolus capreolus) fawns. This was found in both sexes and whatever the year of birth. Thus, the initial maternal investment, by way of birth and growth rate during the first weeks of life, seems to play a role only during the summer part of the juvenile period in this roe deer population, which exhibits a high productivity. This result could directly depend on the availability of food resources in summer and autumn, rather than on the species of ungulate. When abundant food resources are available to ungulates prior to the winter, the lesser importance of early development could buffer the differences of lifetime reproductive success between cohorts.Resume. -A partir de 65 faons marques dans la reserve de Trois-Fontaines (est de la France) quelques jours apres leur naissance et recaptures dans leur premier hiver, nous demontrons l'absence de relation entre croissance precoce et poids ä l'entree de l'hiver chez le faon de chevreuil (Capreolus capreolus). Ceci apparait quels que soient le sexe et l'annee de naissance du faon. L'investissement maternel initial, par l'intermediaire du poids de naissance et du taux de croissance pendant les premieres semaines de vie, semble done avoir un röle limite ä la phase estivale dc la periode juvenile dans cette population de chevreuils caractorisee par une forte productivite. II semble que ce resultat soit plus directement lie ä la disponibilite des ressources alimentaires en ete et automne qu'ä 1'espece consideree. Dans les populations beneficiant d'une riche disponibilite des ressources alimentaires, cette moindre importance du developpement precoce pourrait tamponner les differences de succes de reproduction ä long terme entre cohortes.
In previous papers we reported a deficit of tyrosine (TYR) and tryptophan (TRP) transport across the erythrocyte membrane in depressed patients. To investigate further the transport mechanism of both monoamine precursors, we tested in healthy subjects the role played by membrane fluidity, using different fluidizing agents such as alcohols and the neuroleptic chlorpromazine. We found that the transport of both amino acids depended on the length of the chain of each alcohol tested (number of carbon atoms = C). No inhibition was observed after methanol (C1) preincubation, in contrast to benzyl alcohol (C6), which produced an inhibition of about 80% of amino acid basal transport. In a condition of incubation by suspension of cells in an artificial medium, we observed a dose response of these transports with ethanol used at doses of 0.1–1.3 M. Finally we found in this study that the effect of ethanol on membrane fluidity, and therefore on inhibition of basal amino acid transport, was totally reversible after having washed the suspended cells, suggesting a superficial, noncovalent ethanol binding on such biological membranes.
We demonstrate in the present work that wrong assessment of age can markedly affect the interpretation of vertical life tables. We built such a life table from a sample of known age roe deer considered as representative of a fictional population. Mean survival rate in adult stage was then 0.51, leading to a decreasing population (-10 % per year) by using a demographic model. Conversely, 5 out of 8 age structures estimated by different people (3 specialists, 3 well-trained and 2 inexperienced people) from wear tooth criteria well-defined for roe deer led to overestimate survival. In these cases, estimates led to conclude that the fictional roe deer population was either stable (1 case) or increasing (4 cases). This outcome was independent on the relative experience of observers : age assessment by 2 specialists, 1 well-trained and 1 inexperienced people led to increasing population. Because most previous works focussed on large mammals were based on similar wear tooth criteria, wrong age assessment is likely to occur. This may invalidate interpretations of vertical life tables as well as the violation of both stationarity of the population and representativity of the sample that have received much more attention.Resume. -Nous d£montrons dans ce travail que des erreurs de determination de Tage peuvent avoir des consequences importantes dans l'interprotation des tables de vie transversales. Ainsi, une table de vie transversale construite ä partir d'un echantillon de chevreuils d'age connu indique un taux de survie adulte moyen £gal ä 0,51. L'utilisation d'un modele demographique conduit alors ä une population fictive de chevreuils declinante au taux moyen de 10 % par an. Au contraire, 5 des 8 structures d'age estim^es par des observateurs diff&ents (3 spocialistes, 3 habitues et 2 bootiens) ä partir des criteres d'usure dentaire bien e*tablis pour le chevreuil conduisent ä surestimer le taux de survie et par la concluent ä la stabilite* (l cas) ou ä la croissance (4 cas) de cette meme population fictive. Ceci apparait independant du niveau d'exp£rience des observateurs: les structures d'age determine'es par 2 spe"cialistes, l habituo et l bootien conduisent ä des populations croissantes. Comme la grande majorite* des travaux realisos sur les tables de vie transversales de grands mammiferes reposent sur des criteres d'usure dentaire similaires ä ceux utilises dans notre otude, des erreurs de determination d'äge sont probables et pourraient invalider les conclusions au meme titre que le non-respect des hypotheses de stationnarito de la population et de representativite de l'e*chantillon prelev6 plus classiquement evoquees. , t. 58, n° 2,1994 : 293 · 299. Mammalia
In previous papers, we reported a deficit in tyrosine (TYR) and tryptophan (TRP) transport across the erythrocyte membrane in depressed patients. To investigate further the transport mechanism of the two precursors of monoamines, we tested in healthy subjects the role played by sulfhydryl groups (SH). These groups, cysteine residues, are localized on the intrinsic domain such as the transporters of chloride or sugars. We found that all sulfhydryl reagents that inactivated the SH induced a strong inhibition of the transport of amino acid across the red cell membrane when incubated in the plasma as medium. We concluded that a relationship might exist between these neutral amino acids and D-glucose transport.
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